1. Field of the Invention
The present invention relates to control apparatus and method for optimally controlling a damping force characteristic of a suspension system of an automotive vehicle, the suspension system having four shock absorbers, each shock absorber being interposed between an sprung mass of the vehicle body and an unsprung mass of a corresponding one of front left and right and rear left and right road wheels.
2. Description of Background Art
A PCT Japanese Patent Application First Publication No. Heisei 4-500490 having an international publication No. W091/00187 exemplifies a previously proposed semi-active suspension system for controlling a damping force of each shock absorber interposed between a sprung mass of a vehicle body and an unsprung mass of a corresponding one of front left and right road wheels and rear left and right road wheels.
In the disclosed semi-active suspension system, a dynamic vehicular running state is detected by means of a sensor, a control signal which is used to control the damping force of each semi-active shock absorber mounted along each road wheel of the vehicle is formed on the basis of the sensed dynamic vehicular running state, and a vehicular body behavior is controlled in accordance with the control signal value and actual damping force exerted from each of the semi-active shock absorber.
However, the disclosed suspension system is not designed to take a change in a weight of load applied to a vehicle body from an originally designed weight of load to the present weight of load applied to the vehicle body into the consideration of the control of the damping force of at least one of the semi-active shock absorbers.
Although it is possible to detect a change in the weight of load applied to the vehicle body according to a change in a vehicular height by using a vehicular height sensor, the use of the vehicular height sensor brings out an increase of cost manufacturing the vehicular semi-active suspension system.